<?php
    include "../inc/dbconn.php";
    $sql="select * from ppt  order by Id asc limit 0,48";
    $res = $mysqli->query($sql);

    for($i = 0; $i < $res->num_rows;$i++){
        $data[] = $res->fetch_assoc();
    }

    print_r(json_encode($data));
?>